1. Field of the Invention
The present invention relates to a device for adjusting the position of a multiple-beam laser diode, used for a laser-beam scanning system, relative to a circuit board on which the multiple-beam laser diode is mounted. The present invention also relates to an adjustable conductive support therefor.
2. Description of the Related Art
Various types of laser-beam scanning systems are generally used for laser-beam printers or copiers as means for scanning a photoconductive surface of a photoconductive drum to write an image thereon. In recent years, in order to satisfy the demand for an increase in the scanning speed and the number of pixels per unit of area, a multi-beam laser scanning system has been proposed which makes it possible to write a plurality of scanning lines at each scanning sweep by emitting a corresponding plurality of laser beams at a time, which are separate from one another at predetermined intervals in the sub-scanning direction.
FIG. 10 shows fundamental elements of such a multi-beam laser scanning system. This system is provided with a multiple-beam laser diode 1, a laser-diode-driver circuit board 2, a collimating lens 3, a cylindrical lens 4, a polygon mirror (rotary light-beam deflector having a plurality of reflecting mirrors) 5, an fxcex8 lens 6 and a reflecting mirror 7. The multiple-beam laser diode 1 is fixed to the laser-diode-driver circuit board 2.
The multiple-beam laser diode 1 outputs a plurality of laser beams. These laser beams are each collimated through the collimating lens 3. Subsequently, these collimated laser beams are made incident upon the polygon mirror 5 via the cylindrical lens 4. The polygon mirror 5 is driven to rotate at a predetermined rotational speed by a motor (not shown), so that each laser beam that is incident on the polygon mirror 5 is deflected by the polygon mirror 5, in the main scanning direction, onto a photoconductive drum 8 via the fxcex8 lens 6 and the reflecting mirror 7. The plurality of laser beams which are incident on the photoconductive drum 8 are simultaneously deflected in the main scanning direction to scan a surface (photoconductive surface) of the photoconductive drum 8, to thereby form a corresponding plurality of main scanning lines on the photoconductive surface. The emission of each laser beam is turned ON and OFF in accordance with given image signals to draw a corresponding image (charge-latent image) on the photoconductive surface of the drum 8. Note that only one laser beam is shown in FIG. 10 for the purpose of illustration.
When finely adjusting the intervals of the plurality of laser beams in the sub-scanning direction, the multiple-beam laser diode 1 is usually rotated as shown in FIGS. 11A and 11B to adjust an interval D (shown in FIGS. 11A and 11C) of two scanning lines on the photoconductive drum 8 to an appropriate interval d (shown in FIGS. 11B and 11D). In FIGS. 11A and 11b the collimating lens 3, the cylindrical lens 4, the polygon mirror 5, the fxcex8 lens 6 and the reflecting mirror 7 are represented by a single optical system xe2x80x9cAxe2x80x9d for the purpose of illustration. In a conventional multi-beam laser scanning system, a plurality of leads which come directly out of the bottom of the laser diode 1 are soldered to the laser-diode-driver circuit board 2. Therefore, when finely adjusting the intervals of the plurality of laser beams in the sub-scanning direction, the laser-diode-driver circuit board 2 needs to be shifted, e.g., from an initial position shown by a one-dot chain line to a position shown by a solid line in FIG. 12, or leads 9 of the laser diode 1, which are soldered to the laser-diode-driver circuit board 2, need to be twisted to rotate the laser diode 1 relative to the laser-diode-driver circuit board 2 as shown in FIG. 13. Accordingly, the intervals of the plurality of laser beams in the sub-scanning direction cannot be easily adjusted.
An object of the present invention is to provide a multiple-beam laser diode adjusting device which makes it possible to easily and finely adjust the intervals of the laser beams in the sub-scanning direction, which are emitted from the multiple-beam laser diode, without shifting the circuit board, to which the multiple-beam laser diode is fixed, or twisting the leads of the multiple-beam laser diode.
Another object of the present invention is to provide an adjustable conductive support which is used for such a multiple-beam laser diode adjusting device.
To achieve the objects mentioned above, according to an aspect of the present invention, a multiple-beam laser diode adjusting device is provided, including a multiple-beam laser diode which emits a plurality of laser beams; a circuit board on which a circuit for controlling a laser-emission of the multiple-beam laser diode is mounted; and an adjustable conductive support, positioned between the multiple-beam laser diode and the circuit board, which allows the multiple-beam laser diode to be rotated relative to the circuit board while ensuring an electrical connection between the multiple-beam laser diode and the circuit board.
Preferably, the adjustable conductive support includes a fixed member which is fixed to the circuit board, and a movable member to which the multiple-beam laser diode is fixed. The movable member is mounted on the fixed member to be rotatable together with the multiple-beam laser diode relative to the fixed member while ensuring the electrical connection between the multiple-beam laser diode and the circuit board.
Preferably, the multiple-beam laser diode includes a plurality of terminal leads, the movable member including a corresponding plurality of first conductive portions which are electrically connected with the plurality of terminal leads, the fixed member including a corresponding plurality of second conductive portions which contact the plurality of first conductive portions, respectively, to ensure the electrical connection between the multiple-beam laser diode and the circuit board, and the adjustable conductive support including a device which restricts rotation of the movable member within a predetermined rotational angle, wherein each of the plurality of first conductive portions is electrically connected with only a corresponding one of the plurality of second conductive portions and disconnected from any other of the plurality of second conductive portions.
According to another aspect of the present invention, an adjustable conductive support includes a movable member to which a multiple-beam laser diode is fixed, and a fixed member which is fixed to a circuit board on which a circuit for controlling a laser-emission of the multiple-beam laser diode is mounted. The movable member is mounted on the fixed member to be rotatable together with the multiple-beam laser diode relative to the fixed member while ensuring the electrical connection between the multiple-beam laser diode and the circuit board.
Preferably, the multiple-beam laser diode includes a plurality of terminal leads. The movable member includes a corresponding plurality of first conductive portions which are electrically connected with the plurality of terminal leads. The fixed member includes a corresponding plurality of second conductive portions which contact the plurality of first conductive portions, respectively, to ensure the electrical connection between the multiple-beam laser diode and the circuit board. The adjustable conductive support including a device which restricts rotation of the movable member within a predetermined rotational angle relative to the fixed member, wherein each of the plurality of first conductive portions is electrically connected with only a corresponding one of the plurality of second conductive portions and disconnected from any other of the plurality of second conductive portions.
In the above described aspects of the present invention, preferably, each of the plurality of first conductive portions remains in slidable contact with a corresponding one of the plurality of second conductive portions. Preferably, the movable member includes a first cylindrical body and two first protrusions which extend radially from the first cylindrical body in opposite directions. The fixed member including a second cylindrical body and two second protrusions which extend radially from the second cylindrical body in opposite directions. The adjustable conductive support including a fixing device for fixing the two first protrusions to the two second protrusions, respectively, the fixing device including at least one pair of screw bolts and at least one pair of corresponding screw nuts.
The present disclosure relates to subject matter contained in Japanese Patent Application No. 11-2426 (filed on Jan. 8, 1999) which is expressly incorporated herein by reference in its entirety.